1. Field of the Invention
This invention relates generally to control units for photographic film printers and particularly to an improved printer control unit capable of operating several of the most common commercially available printing modes.
2. Description of the Prior Art
Photographic film printers are widely used in the motion picture industry for the improvement of photographed scenes with respect to image density, composition, color balance, fading, and other special effects.
Typically, optical changes such as color and light intensity and fading or special effect information is provided on a coded control tape. The tape is preprinted with rows of control data to be sequentially read by an appropriate tape reader to accomplish the desired printer operation at the film frame line at the beginning of a particular scene. Therefore, a cue or cue signal is necessary to initiate the actuation of the printer operations.
Two cuing systems, notch and RF patch, are commonly employed to provide cues to the printer. The notches or RF patches are applied directly to the preprint film so that the appropriate cue is generated as the notch or patch is sensed. However, both the notch and patch systems have not proven entirely satisfactory, particularly in view of the high speed at which modern printers operate and because of the required physical handling to prepare the master preprint film.
Therefore, a number of automatic cuing systems or frame counting cuers have been developed which use a second coded tape carrying cue address information to provide the cue signals. Automatic cuing thus obviates the need to physically alter the master preprint film in order to provide cue signals to the printer. In frame count cuing systems, the movement of the film through the printer is continuously monitored. Control information concerning light changes and the like is transferred to the printer. This is done upon the occurrence of a predetermined relationship between the monitoring counter and film address information provided by the cuing tape.
Other devices have also been provided in an attempt to combine both the control information and film address information on a single control tape. However, such approaches have not proved completely satisfactory from a standpoint of reliability, speed and versatility. Moreover, none of the above systems are compatible with one another such that a user can employ new devices utilizing advanced techniques without losing the use of existing equipment, control tapes and the like.